Telephone system.



H. G. WEBSTER.' TELEPHONE SYSTEM. ,APPLIOATION FILED SEPT. 20,1906.

Patented. 5,

emana es mam more,

HARRY G. WEBSTER, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNHIEN'IS, TO

KELLOGG SWITCI-IBOARD 8c, SUPPLY COMPANY, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

meas es.

Specification of Letters Patent.

' Patented Jan. 5, 1915.

Application filed September 20, 1906. Serial No. 335,419.

To all whom it may concern:

Be it known that I, HARRY G. VVEBs'rEn,

a citizen of the United States, and residing at Chicago, county of Cook, and State of- Illinois, have invented certain new and useful Improvements in Telephone Systems, of

which the following is a specification.

My invention relates to telephone exchange systems and particularly to that type in m which link-conductors are interchangeably associated with the subscribers lines, mechanism being provided for each subscribers line which is automatically actuated, when the receiver is taken for use, to connect" the subscriberfs line to an idle link-circuit.

In the embodiment of the invention disclosed in the present applicatiomeach linkcircuit is provided with a manually controlled terminal, and the connection of a subscribers line to the link-circuit displays a calling signal locatedbefore an operator, who may then, upon learning the wishes of the calling party, complete the connection to the desired called line.

The principal object of the present invention is to provide improved means for securing the connection of the subscribers line to an idle link-circuit in a structure characterized by simplicity and positiveness so of operation and economy of manufacture.

Other objects of my invention are to provide means in structures-of this particular character for preventing the disconnection of the link-circuit when the subscriber replaces his receive-r after connection is established; to provide means for preventing the operation of the automatic mechanism I through an accidental ground on the outside limbs of the line; to provide automatic to means for disconnecting such grounded line limbs; and to provide means for givi' g an indication of such disconnection. I

Still other objects of my invention will be apparent from the following description. In accordance with my invention, I provide for each subscribers line a traveling switch which is preferably adapted to carry movable contacts in a rotary direction when a link-circuit is to be selected, and to restore 5o them in the reverse direction at the time of disconnection. This switch, is operated by step-by-step mechanism, preferably actuated by current from a pulsating generator. The switch is provided with three moving con- 5 tacts or wipers which constitute the terminals individual to the line, and with fixed contacts adapted to be engaged thereby, which constitute terminals of the circuits in dividual to various link-conductors. These link-conductors terminate preferably in .cords and plugs at various operators positions of a multiple switchboard, and the subscribers lines are provided with multiple jacks at the multiple sections.

I do not wish, however, to be limited is a this means of connecting the link-circuits to other lines.

The two moving contacts or Wipers of the switch, which correspond to the line limbs, have a normal position in which they do not engage any of the fixed contacts of the switch, and the third or private wiper normally engages a contact directly connected to earth or the return side of the centrai battery. Vhen rotated, the wipers will engage preferably, first, the contacts connected to a link-circuit terminating at the first operators position; then, contacts connected with a link-circuit at the second operators position; then, those leading to a third operators position, and so on; and these fixed contacts are multiply connected on the simi lar switches individual to other subscribers lines in a group. The other link-circuits, terminating at the first, second, third and other operators positions, may be similarly connected to the switches of lines in other similar groups. The arrangement is such that if the link-conductors, connected to the first contacts of a particular group ofswitches, be in use, the switch will step ahead to the second contacts, and so on until an idle link-circuit is reached; when it will come to rest and the operation of associated mechanism will connect the line limbs to the talking conductors of the link-circuit and cause the display of a calling signal associated'therewith. The operator, after ascervtaining what connection is desired,-tests the multiple jack of the desired line, makes connection by the insertion of the plug, and rings the subscriber in the usual way. When the plug is inserted into the jack of the de sired line, the operation of a cut-off relay as sociated with that line disconnects its traveling switch and associated mechanism. \Vhen the receivers have been replaced at the tor mination of conversation, the removal of the connecting plug causes the deenergizatior of a magnet, an the retraction of the arma be operated to disconnect ra a:

ture of this magnet releases the mechanism of-the switch and allows the wipers to return to their normal position by spring tension.' The organization is such that if that 1 line limb, associated with the active terminal of the battery, become accidentally grounded, the switch will not start to move,

subscriber attempts to call and the heat-coil,

will likewise be operated to disconnect the first line limb unless the receiver is immediately replaced. The heat-coil can likewise be operated by means of an operators ky,

should the two limbs become directly connected together. Should the circuit of the limbs be momentarily closed, as if theire- 'ceiver were raised and immediately replaced, the switch would stop with its wipers engaging the contacts of a busy or an idle linkcircuit, but the line limbs would not be then connected to the wipers, nor would the linkcircuit be excluded from use by other lines.

To secure the propercperation of the apparatus, I provide a relay connected be tween one linelimb and the active terminal of the battery, which serves, when operated, to complete a circuit of a local relay magnet controlling the. connections I of the line wipers, which are, normally disconnected from the linelimbs. This relay is nbrmally short circuited throughthe direct, earth connect1on of a normahcontact with a private wiper. I provide a 'second relay normally connected between the return side of the 'tion of the driving-magnet of the switch.

The operation through battery and the opposite line limb, which serves, when energized, to cause the operaof both line relays is therefore required to cause the connection of the line'to an idle link-circuit; and if the firstmentioined line relay alone operate, as the presence of an accidental ground, it will include the previously men- .tioned heat-coil in circuit with the direct earth connection .of the private wiper and cause its operation within any desired time. The local relay is energized when connection is established to the link circuit; and is denergized at the time of disconnection to disconnect thefhne wipers, and to release the mechamsm of the switch, allowing them to return to normal. When the connecting plug of the link-circuit is inserted into the jack of'the desired line, a circuit is ,then established forthe first-mentioned which maintains its energization independefritly of the circuit through the substation andthus prevents the decnergization of-the local relay unti-Lthe plug is-removed.

My invention will be morefn understood line relay,

ergization of relay 5 from the accompanying drawing which rep-- resents two subscribers lines with their traveling switches, and a suitable link-circuit apparatus, all organized in accordance with a preferred form of my invention.

Like characters refer to corresponding parts in the drawing.

Referring to the drawing, lines A and A are each provided with the usual bell and condenser in permanent bridgc'of the line, and with a receiver '1" and transmitter 5 adapted to be included in circuit by the elevation of the switch-hook ii.

The limbs l and 2 extend to the central oflice and are there connected to the central battery G.

A rotary switchS is provided for each line, which is diagrammatically indicated as having a ratchet-wheel 80 and wipers a, b, 0, carried on a shaft 16, the switch being driven with a step-bystep motion by the motor-magnet 22 when circuit is closed through the pulsating generator G.

vThe driving pawl 23 is normally out of engagement with the wheel 80.

The wipers a and b are associated with limbs l and 2 of the lineresl'pcctively; and when the shaft is rotated by the action of themagnet 22, they engage" the contact pieces or fixed contacts a, a? and [1,0 i'e-'.

circuits of 'the structure. It normally rests upon the contact-piece connected to the re turn side of the battery C as indicated; and when rotated, it engages contact 0; and in stepping from 0' to 0 engages a before disengaging c, and likewise with the other contacts over which it wipes.

The fixed contacts are diagrammaticall 1 indicated as inultiplycoiinectcd to corre- .sponding contacts of other switches in the same group of lines, such other switches being indicated at. S.

The first contact-pieces are to be under stood as connected to the wires of a liiili circuit terminating in a cord and plug at the first operators position; the second, contact-pieces to a similar circuit at a second operators position; and so on through all of the contacts ofthe switch.

The ratchet-wheel is provided with a 1'C- taining pawl 26 controlled by the attraction and release of armature 29 of the local rc lay 5. When the shaft 16 is rotated by the action of magnet 22, the retaining pawl 26 prevents the restoring spring 81 from returning the shaft to its normal position. After the switch has made one step, the enwill cause the moving member 28, carried by armature 29: to engage the projectiiig arm-of the rztaining lili.

Jan.

masses rangement is indicated at B. When a subscribed desires-to initiate a call, the removal of his receiver closes a circuit which may be traced as follows: from the upper terminal of the battery C, through line, relay 3,- contacts 78 of the cut-off relay 4, contact 9 and spring 10 associated with the heat il 11, limb 2, receiver r and transmitter} i,

limb 1, contacts 12-13 of the cut-off relay,-

contacts 1415 of the local relay 5 and vto thelreturn side of the battery through the winding of relay 6. This current energizes relays 3 and 6 and operates their contacts.

Contact 17- of relay 3 disengagcs contact 32 and engages contact 18, thus disconnecting the cut-cit relay 4 from its normal ground connection and connecting it to the vides a path for battery "from the upper terminal of battery-C, through protective resistance 99, contacts 1817, resistance 19,

contacts 2120, the winding of heat-coil 11, and to the return side of the battery through wiper c and the contact-piece upon which it normally rests. This circuit is of but noinentary'duration normally; but if it be maintained for an abnormal length of time, will cause the operation of the heat-coil 11. The energization of relay 6, however, has caused the engagement of its contacts 31-32, thus completing the circuit of the pulsating generator G through magnet 22, and this starts the rotation of the switch. As will be subsequently shown, the contacts of all busy link-conductors .are'normally conaected to the return side of the battery through wire 82 of the connected switch. As long, therefore, as wiper 0 passes over such contacts, relay .5 is shunted by the connection from resistance 19, through contacts,

When, however, an un-' shunt circuit of relay is broken and the relay energized. The operation of its contact 20 disconnects the wiper c and heat-coil 11 from the circuit of relay 5 and connects them directly to the return side of the batte ry at contact 33.

The operation of the contact controlled by armature 29 interrupts the circuit of magnet'22 at contact 30. The operation of contact 14, which engages contact 37 and subsequently disengages contact 15, disconnects relay 6 and connects limb 1 of the line to the line wiper a which is now resting on contact a, and the operation of contact 34 connects relay 3 and limb 2 towiper Z) at contact 35. It will be understood that the heat-coil will not be operated during the short time while the wiper c is passing over busy contacts.

i Circuit may now be traced from battery C, through relay 3, contacts 78, limbs 2 and 1, wiper a, contact a, wire 38 and re lay 40 to the return side of the battery. This circuit energizes relay 4:0 and the operation of contact 44 completes a circuit for illuminating lamp 65 through contact 45 and contacts 47l8 of relay l3. Upon observing the illumination of the lamp, the operator actuates her listening-key levers 7c and ascertains the wishes of the subscriber A. As suming A to be the one desired, the operatip of her connecting plug P to the contact of the jack j of that line. If the line be busy, the potential of contact 56 will be raised either through the presence of another connecting plug in a corresponding jack, or

through the operation of relay 3 of that line, as already pointed out. In either case, current will then flow from contact 56, through strand 54, contact 52 and thence through test winding 53 of the operators 43 and 4 are thus energized and the operation of relay 4 disconnects the line limbs T r from relay 3 and relay 6 and connects them to the talking terminals of the springjack. Belay 43being also energized, the operation of contact 48, disengaging contact-l7 and engaging contacts 49 and 50, interrupts the circuit of lamp 66 and connects the impedance coil 42 to the return side of the battery A second energizing circuit is thus providedfor relay 3 of the calling line A,

which may be traced from the upper termirial of thebatteryC, through the winding of relay 3, wire 36, contacts 34-3r1 wiper 7), contact 6, wire 39, impedance 42, contact 49 and contact 48 to the return side of the battery.

This energizing circuit is. main- -tor tests in the usual way by applying the I wipers,

eration oi ont? winding re pawl 24.

cei er.

The operation of of relay 43 completes the circuit of l through th contacts 59- I and the oph test Windingfroi' v and coinpletes the circus of trend through the .T The operator then 1 e usual manner, a i sing provided to prevent the vibrati y 4-3 by cur; rent i'rom the alternating generator G during ringinm l fhen the subscriber answers,'currings subs-ct rentwill flow from batter; C, through recontaot contact 8, i, n act 12, contact 83 of the strand c ay all to the El y j. 116

lay 43, strand limbs l and 2? co springiaclr, return. side of the operation: of contact 60 of .l the lamp 66 and the two subscribers are united for conversation through condensers 5'7 and '58. l i hen either subsc iber up his receiver, the deenergizatlon of relay 460 or 41 causes the illumination oi lamp. lVllQT-l both lamps are illuminated, the operator removes the con ccting plug and the circuits of i1 return to their normal condition.

Belay being thus deea d l-8 fl-9 are disengaged, inierrup ri the circuit through relay 3 of line A. The consequent operation or" its contact 17 restores contacts the circuit of the cut-oil." relay and interrupts the circuit At ti tion of relay 5 1 vertical arm of e energizesection, the i er a retraction of thi throws pawl 26 out oi? cngagcnieit with ratchetvvhcel 80, and the restoring spring 81 carries the shaft and wipers to their normal oosition the rejecting piece 25 engages As this position is reached, projection 27, also moving with the wheel, throws member 528 out pawl 26, allowing the saw] return engagement with the ratclPt-whoci. limb 2 of the line become accidcntallv nccted to ground throug "my which will cause the ope, relay 6 is then uncnergized: closed through contacts f ll, resistance 19, heat-coil l1 and wiper c, is thus maintained until the heat-coil 0 es, which time spring 63 em the illuminatiiiin 0. operation, and the dis 15G from contact 9 l of relay 3,

-1 Y. v 1 r howing ielay 5 disconnects its associated of engagement with grounded, a similar action will take place w ion the subscriber attempts to call, if his switch-hook be then lifted for the length of time necessary cause the operation of the heat-coil.

If the subscriber operate his switch-hook intermittently, the switch will step ahead each time circuit is closed. If the hook be depressed after th idle link-circuit has been selected, the switch will immediately ielease by the means previously described. If the hook, however, be depressed before such idle circuit ha" been selected, the switch will stop with its wipers-in engagcmeat with the contacts 01' an occupied cordcircuit. g

The resistance 19 is so proportioned to the resistance of heat-coil 11, and to that of relay 5, that the relay of the connectedlinc will not be released at this time; and wipers (2' and bof the line being disconnected at contacts 37 and 35, no interference with the occupied ci "cuit will result. When the connected line is released, the wipers of line A will still remain upon the contactsof the c rd-circuit, but the link-circuit may be selooted by another calling line, by reason of resistance 19 being so proportionedas to allow the relay 5 of the calling line to be energized at this time. Relay 5 of line A does not at this time get sullicient current to operate it. lVhen subscriber A subsequontly elei 'ates his switch-hook, if the linkconductor at that instant be busy his switch will step ahead and select another idle linkcircuit. If the link-circuit at that instant be idle, however, his relay 5 will be immediately energized, thus maintaining his connection with the cord-circuit and causing the illumination of the calling signal 65. Should the two line limbs become accidentally connected togethcin the cord would be selected and the signal displayed as if the subscriber were calling. When the operator attempted to answer and received no response, she would understand the nature of the condition and depress her key If, thus completing a circuit from battery C, through key 717 wire 98, contact 0, wiper 0, wire 82, heatcoil 11, and contacts 2033 to the return side of the battery. The heat-coil is thus operated, opening the circuit of line A. at contacts 10-9, deenergixing relay 3 and restoring the wipers to normal. The same method may be followed in case a. subscriber fail to replace his receiver. Means thus provided whereby certain abnormal conditions shall not cause the switch to operate, but shall cause the line to be disconiiected from the central battery and an ind es displayed. Means are thus likewise ov-o'vucd whereby, if a line become conwziied to a link-circuit under other abnorniai conditions. the operator may cause the obvious that many other values may equally well be employe It is to be understood that the batteries C and C may be the same, and that the several grounds indicated may be a common return. It is obvious that many modifications may be made in my invention without departing from its spirit and I do not wish to be limited to the precise structure illustrated and rescribed.

That which I consider new and novel and desire to secure by Letters Patent of the United States is 1. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch for the line having movable contacts operating to select an idle link-circuit and connect the line thereto, restoring means for said switch, and means responsive to current in both limbs but not to current in the active limb alone for causing the operation of said switch whereby said line is connected. V A telephone exchange system c'ompris ing a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch for the line having movable contactsoperating to select an idle link-circuit and connect the line thereto, a local circuit, a heat responsivedevice included in said local ClI- cuit, and means responsive to an abnormal current flow in said line to actuate said device to permanently disconnect said active limb from said sourc A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the'active terminalof said source and an opposite limb normally connected to the grounded terminal of saidsource, a traveling switch tor the line having movable contacts operat ing to select an idle link-circuit and connect the line thereto, and locally controlled heat pensive means to disconnect said active .h from said source.

driving means for said switch,

4. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb '7 normally connected to the grounded terminal of said source, a traveling switch for the line having movable contacts operating to select an idle link-circuit and connect the line thereto, and locally controlled means to disconnect said active limb from said source, said means being automatically operated in response to current in said active limb but not in response to current in both limbs.

5. A telephone exchange system compris- 8Q ing a grounded source of current, aplurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded 5 terminal of said source, a traveling switch for the line having movable contacts operating to select an idle link-circuit and connect the line thereto, locally controlled means to disconnect said active limb from said source, 0

and means whereby current in the active limb will operate said locally controlled means and current in both limbs will not 0perate said locally controlled means.

6. A telephone exchange system comprising a grounded source of current, a plurality of'linlr-circuits, a telephone line having an active limb normally connected to the active terminal ofsaid source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch for the line having movable contacts operating to select an idle link-circuit and connect the line thereto, locally controlled means to disconnect said active limb from said source,

and manual means associated with a linkcircuit for causing the operation of said locally controlled means.

7. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch for the line having movable contacts operating to select an idle linlecircuit and connect the line thereto, locally controlled means to disconnect said active limb from said source, means whereby current in the active limb will operate said locally controlled means and current in both limbs will. not operate said locally controlled means,

and manual means associated with a linkcircuit for causing the operation of said locally controlled means.

8. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active lat) of link-circuits,

a selection of said link-circuit.

9. A telephone exchange system comprising a grounded source of current, a plurality a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a travelingswitch for the line having movable contacts operating to select an idle link-circuit and connect the the operation of line 1s connected, 30

line thereto, driving means for said switch, restoring means for said switch, means responsive to current in both limbs but not to current in the active limb alone for causing said switch whereby said and a relay responsive to current changes in the line, after the line is connected to a link-circuit, for causing the operation of the restoring means.

10. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch for the line having' movable contacts operating to select an idle link-circuit and connect the line thereto, driving means for moving said contacts in one directionto connect said line 'to a lin -circuit, restoring means for moving said contacts in the reverse direction to disconnect said line, and means whereby an abnormal earth connection to the active limb does notcause the operation of said driving means.

11. A telephone exchange system com-- prising a telephone line extending from a substation to an exchange, a plurality of a sociated link-circuits, a traveling switch for said line having movable contacts operating to select an idle link-circuit and connect the line thereto, andmeans whereby an abnormal earth connection to the'line does not cause said operation of said switch.

12. A telephone exchange system comprising a telephone line extending from a substationto an exchange, a plurality of associated link-circuits, a traveling switch for said line having movable contacts operating to select an idle link-circuit and conmeet the line thereto, driving means for having an active .the active nmasae moving said contacts in one direction to connect said line to a link-circuit, restoring means for moving said contacts in the reverse direction to disci'innect said line, and means whereby an abnormal circuit for the line limbs does not cause a link-circuit to be permanently excluded from selection by the switches of other normal lines.

13. A telephone exchangesystem comprising a telephone. line extending from a sub station to an exchange, a plurality of associatcd link-circuits, a traveling switch for said line having movable contacts operating to select an idle link-circuit and connect the line thereto, driving means for-moving said contactsvin one direction to connect said line to a linlccircuit, restoring means for moving said contacts in the reverse direction todisconnect said line, and means'for preventing a short circuit of the line from causing a link-circuit to be permanently occupied to the exclusion of normal similar lines.

14. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal ottsaid source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch for the line having movable contacts OIJBlfilIlg to select an idle link-circuit and connect the line thereto, driving means for moving said contacts in one direction to connect said line to a link-circuit, restoring means for moving said contacts in there verse direction to disconnect said line, and means responsive to current in both limbs but not to current in the active limb alone for causing the operation of said switch whereby said line is connected.

15. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch for he line having movable contacts operating to select an idle linkcircuit and connect the line thereto, and an electrically operated switch in a local circuit operating -to disconnect said active limb from said source, said switch being automatically operated in response to' current in said active limb but not in response to cur rent in both limbs,

16. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, -a telephone line limb normally connected to terminal of aid source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch forthe line having movable conswitch for the earse tacts operating to select an idle link-circuit and connect the line thereto, an electrically operated switch in a local circuit operating to disconnect said active limb from said source, said switch being automatically operated in response to current in said active limb but not in response to current in both limbs, and a switch under the control oi the operator for causing the operation of said electrically operated switch;

17. A telephone exchange system comprising a grounded source 01 current, a plu rality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a travel-- ing switch for the line having movable contacts operating to select an idle link-circuit and connect the line thereto, driving means for moving said contacts in one direction to connect said line to a link-circuit, restoring means for moving said contacts in the reverse direction to disconnect said line, and a controlling line relay for said switch so connected that an abnormal earth connection to the active limb does'not cause the operation of said driving means.

18. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch for the line having movable contacts operating to select an idle linlecircuit and connect the line thereto, and a line relay and a local relay for controlling said switch so connected that an abnormal earth connection to the active limb will not cause said operation of said switch.

19. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line haw ing an active limb normally connected to the active terminal of said source and an opposite'limb normally connected to the ground-- ed terminal of said source, a traveling switch for the line having movable contacts operating to select an idle linlecircuit and connect the line thereto, driving means for said switch, and a relay for each line limb for controlling said switch and circuit connections whereby an abnormal earth connection to the acti e limb does not cause the operation of said driving means.

20.. A telephone exchange system comprising a grounded source of current, a pluralityof linlccircuitaa telephone line'haring active limb normally comiected to the active terminal of saia source and an opposite limb normally heated to the ground ed terminal oi? source, a traveling line having movable contacts operating to select an idle link-circuit and connect the line thereto, and a relay for each line limb to control said switch and circuit connections whereby an abnormal earth connection to the active limb does not cause said operation of said switch.

21. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source. andan opposite limb normally connected to the grounded terminal of said source, a traveling switch for the line having movable contacts operating to select an idle link-circuit and connect the line thereto, and an'electrically operated switch for disconnecting the active line limb from said source whereby an abnormal circuit for the line limbs does not cause a link-circuit to be permanently excluded from selection by the switches of other normal lines.

22. A telephone exchange system com .prisinga grounded source of current, a plu circuit for the line limbs does not cause a link-circuit to be permanently excluded from selection by the switch s of other normal lines.

23. A telephone exchange system com; prising a telephone line extend from a substation tov an exchange, plurality of associated link circuits, a traveling switch for said line having movable contacts operating to select an idle linlocircuit and connect the line thereto, driving means for moving said contacts in one direction to connect said line to link-circuit, restoring means for moving said contacts in the re verse direction to disconnect said line, and a line relay, a local relay and circuit connections whereby a short circuit of the line is prevented froin causing a link-circuit to be permanently occupied to the exclusion of normal" similar lines.

24. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connect d. to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch. for the line having movable contacts operating to select an idle-linlecircuit lit and connect the line thereto, other telephone linesand manual means for connecting" a selected link-circuit'to one of said other telephone lines, and means whereby when the line is connected to a link-circuit and circuit 1s closed through the line limbs an operator may cause the active limb of the line to be disconnected from said centra source.

25. A telephone exchange system com prising a telephone line extending from a substation to an exchange, a plurality of associated link-circuits, a traveling switch for said line having movable contacts operating to select an idle link-circuit and connect the line thereto, other telephone lines and manual means for connecting a selected link-circuit to one of said other telephone lines, driving means for said switch, restoring means for said switch, and means where by when the line is connected to a link-circuit and circuit is closed through the line limbs an operator may cause the operation of said restoring means.

26. A telephone exchange system comprising a telephone line extending from a substation to an exchange, a plurality of associated link-circuits, a traveling switch for said line having movable contacts operating to select an idle link-circuit and connect the line thereto, other telephone lines, and manual means for connecting, a selected link-circuit to one of said other telephone lines, driving means for said switch, and

means wherebywhen the line is connected to a link-circuit and circuit is cl. sed through I the line limbs an operator may cause said switch contacts to move to their normal position and come to rest.

2'7. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, traveling switch for the line having movable contacts operating to select an idle link-circuit and connect the line thereto, other telephone lines and manual means for connecting a selected link-circuit to. one of said other telephone lines, driving means for said switch, restoring means for saidswitch, and means whereby when the line is connected to a link-circuit and circuit is closed through the line limbs an operator may cause the operation of said'restoring means and the discon'. nection of the line from the active terminal of said source.

28. A telephone system including a telephone line, a selective switch therefor, a

manually operated switchboard, linlncircuits extending from sa1d switch said switchboard, a line relay for said line for closing a circuit v! on pan 1 i movement of said switch.

upon, (leiiucrgimtion oi id pawl. stem including a ielcis switching: station. circuit TZOEHl-itilllfl' idling lZUllLili la Oi controlling;

n, an enliming. two siiiiul- We coi'il'inuity oi" Elie station of sait t, other lax-inch bcii're; 313 controlled at sa i tion. and means whereby deem :ation of? said relayrcstoressaic .itch.

30. telepn vre in including? a telephone line, line f therefor, a substrtion switch for ca a iiow ot current thorethrough, an opcratorh switch controlling means for establishing a branch of said circuit whereby said relay receives current over two simultaneously closed and inde- .pendently controlled branches, and a selective switch associated with said relay, a retainiI-ig pawl preventing return movement of said switch, and means controlled by the deencrgixation of said relay for witlidrau ing said D Y l from i etaining position.

251. A JLGECL one e .l 1);;0 svstem comprising a grounded source oi iirrent, a telephone line having a limb normall' connected with the active terminal of said hire and an. opposite llfll) normally connected with the grounded terminal of s id source, a phi rality o'l lllll -(ll.( active switch and controlling n ins "si..;; coin crti n of an idle link-circuit will telephone line, and n'icaus to murcnt in both iri ie. but not nt iu. the active liinl alone mechanism of the said switch line is connected to idle l"= 5 comprising a.

plurality of ma, nne having a limb actiic terminal opi'iosite limb nonl2!) iouinlcd to ll liliil to can u; itrolling urea s le lil'ilvt al ci -a heat respomivc salt, curt, and l} SH to act -33. A telephone system comprising a grounded source of current, a plurality of dink-circuits, a telephone line having a limb from said source.

34. A telephone system comprising a grounded source of current, a plurality of link-circuits, a telephone line having a limb normally connected to the active terminal of said. source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch associated with the line and controlling means to cause connection of said line with an idle link-circuit, a' locally controlled heat responsive device serving to disconnect said active limb from said source, and means for automatically operating said device in response to current in said active limb.

35. A telephone system comprising a grounded source of current, a plurality of link-circuits, a-telephonc line having a limb normally connected to the active terminal of said source and an op posite limb normally connected to the grounded terminal of said source, a traveling switch associated with the line and controlling means to cause con nection of said line with an idlclink-circuit,

locally controlled heat responsive means to permanently disconnect the active limb from said source, and manual means associated with the link-circuit for causing the operation of said heat responsive means.

36. A telephone exchange system comprising a grounded. source of current, a plurality of link-circuits, a telephone line having an active limb normally connected with the active terminal of said source and an opposite.limb normally connected with the grounded terminal of said source, a traveling switch and controlling means for causing the connection 01 said line to an idle link-circuit, means responsive to current in both limbs, but not to current in the active limb alone, for controlling the circuit connections of said switch whereby said line is connected, and a relay responsive to current changes in the line, alcr the line is connected to a link-circuit, for dl-s'u-n'it ng saigl link-circuit and line.

3 A telephone exchange system comprising a telephone line extending from a sub station to an exchange, a plurality of associated link-circuits, a selective switch associated with said line having means controlling the connection of said line with an idle link-circuit, said switch being sensitive to current over said telephone line, and means whereby ,an abnormal earth connection to the line does not cause the response of the mechanism of said switch.

38. A telephone exchange system comprising a groui'lded source of current, a plurality of liiilecireuits, a. telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal. of said source, a selective switch associated with said line and controlling means ior causing the connection of sa d.

line with an idle link-circuit, the medhanism of said switch being sensitive to current over said line, and a line relay and .a local relay for controlling said mechanism so connected that an abnormal earth connection to the active limb will not cause the response of the mechanism of said switch.

39. .A telephone exchange system comprising a telephone line extending in two line limbs to an exchange, a grounded source of current at the. exchange, anactive limb of said. line connected. to the active pole of said source and an opposite limb of said line connected with the grounded pole of said source, means for producing a'flow of current in normal quantity over said line, a signal adapted for actuation responsive to a prolonged flow of current in normal quantity over one only of said line limbs, and switch mechanism set in' operation by a flow of current in normal quantity over the other line limb.

40. A; telephone exchange system com prising a tclmahoneline extending in two limbs to an exchange, a central source of current in bridge of said line limbs at tho exchange,asignal common to said line limbs adapted for operation responsive to a prolonged flow of current of normal quantity over one of said line limbs or over said limb and the other line limb when 'conductively united, and switch mechanism-set in operation by a flow of current in normal quantity over said other line limb.

4-1. The combination with a telephone line, of a signal for-said line, means responsive to the initiation of acall at the sub-- station of said line to cause a flow ot current over a limb of said line, heat actuated 'meansresponsive to a prolonged" normal current flow over said line, a s gnal con ftrolljed by said means, and switch mecha- .line, means ior causing allow r current over said line, automatic means at the exchange operable responsive to said current flow to alter the normal battery connections of said line, and a heat controlled device ell'ective iilsaid means fails to alter said normal battery connections.

44:. A telephone exchange system comprising a telephone line extending to an exchange, a grounded source of current at the exchange, an electromagnet included in circuit between one pole of said source ,and one line limb, an electromagnet similarly included between the other pole of said source and the other line limb, a troubleindicating signal, means for actuating said signal in response to a prolonged tlow'of current in normal quantity from said source to said line through one of said magnets only and means normally responsive to a. flow of current through the other of said magnets to prevent the actuation of said signal.

45. A telephone exchange system comprising, a telephone line extending to an exchange, a grounded source of current at the exchange having its live pole normally connected to said line, a control electromagnetic relay included in circuit between the live pole of said source of current and said line, an alarm signal, means for actuating said signal in response to the prolonged energization of said control relay, and means operative under normal conditions to prevent such prolonged energization.

46. A telephone exchange system comprising a telephone line.extending in two line ,limbs to an exclgange, a grounded source of current at the exchange, a control electromagnetic relay included in circuit between the grounded pole of said source of current and one line limb, electrical switching mechanism controlled by said relay, a normal connection between the live pole of said source of current and the other line limb, means for actuating a signal in response to a prolonged flow of current from said source over said other lin limb, and means operative under normal conditi-ons to prevent :such prolonged flow of current.

" 47. A telephone exchange system comprising a telephone line extending in two line limbs to an exchange, .a grounded source oz'r current at the exchange, a control source oi. cur

g a telrelay included in gropnded pole of said. rce oi cu ent and one line limb, a second control relay included in circuit between the live pole ot and the other line l. b, means for act-liming a signal in rcsp to proloiu cue: ion said second control relay, and mean-c nor ally operative in response to the cner'u. ion of said as relay to prevent tl e accrue ion of said si nal.

48. A. telephone exchange system comprising a telephone line cxtendin in two line limbs to an exchange, a grounded source of current at the exchange, a control relay included in circuit between the grounded. pole of said source of current and one line limb, a second control relay included in circult between the live pole of said source of currentand the other line limb, a heat coil lllClUtlCtl in a circuit controlled by said second control relay, a signal. actuated in response to the operation of said heat coil, and means normally operative in response to the cncrgization of said first relay to prevent the actuation of said. signal.

49. A telephone exchange system cornprising a grounded source of current, a plurality of link-circuits, a telephone line haw ing an active limb normally connected to the active terminal of said source and an oppo site limb normally connected to the grounded terminal of said source, a. traveling switchand associated driving and controlling means for establishing connection between said line and an idle link-circuit, locally controlled means to disconnect said active limb from said source, and manual means associated with a linloc'ircuit for causing the operation of said locally controlled means.

50. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch and associated driving and controlling means for establishing connection between said line and an idle link-circuit, locally controlled means to disconnect said active limb from said source, means whereby current in the active limb will operate said locally controlled means and current in both limbs will not operate said locally controlled means, and manual moans associated uith a linkcircuit for causing the operation of said locally controlled means.

51. A telephone exchange system comprising a grounded source of current. a p urality of linlt circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the ground d tcrminal' of said source, a traveling sivitch and lilo switchwhereby said line is connected, and

controlling means for said switch restoringmeans under the control of the substation upon the selection of said link-circuit.

52. A telephone exchange system comprising agrounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch and associated driving and controlling means for establishing connection between said line and an idle link-circuit, restoring means for said switch, means responsive to current in both limbs but not to current in the active limb alone for causing the operation of said switch whereby said line is connected, and a relay. responsive to current changes in the line, after the line is connected to a linkcircuit,'for causing the operation of the restoring means.

53. A telephone exchange system comprising a. grounded source of current, a plurality of link-circuits, a-[telcphone' line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch having movable contacts operating to establish connection between said line and an idle linkcircuit, driving means for advancing said' normal earth connection tothe active limb.

does not cause the operation of said driving means.

A telephone exchange system comprising a telephone line including two limbs extending from a substation to an exchange, a plurality of associated link-circuits, a traveling switch and associateddriving and controlling means for establishing connection between said line and an idle link-circuit automatically upon iifiitiation of'a call over said line, and means whereby an abnormal earth connection to either limb of the line does not cause said operation of said switch.

a telephone exchange system comprising a telephone lin extending from a substation to an exchaige, aplurality of associated link-circuits, a traveling switch having movable contacts operating to establish connection between said line and an idle link-circuit, driving means for ael'vancing said. contacts in one direction to bring about snch connection, restoring means fonmoving said contacts in the reverse direction to dis- COIIHCCl'wSilld line, and means wherebyan abnormal circuit for the line limbs does notv cause a link-circuit to be permanently eX-i cluded from selection by the switches of other normal lines.

56. A telephone exchange system comprising a telephone line extending from a substation .to an exchange, aplurality of asso-- ciated link-circuits, a traveling switch having movable contacts operating to establish connection between said line and "an idle linkcircuit, driving means 'for advancing said contacts in'one directioirtobring about such connection, restoring meansfor moving said contacts in the reverse direction to disconnect said line, and means for prevent ing a short-circuit of the line from causing a link-circuit to be permanently occupied to the exclusion of normal similar lines.

57. A telephone exchange system compris, ing a grounded source of current, a plurality of link-circuits, a telephone line hav-' ing an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded tcrnnnal'of said source, a travel ing switch having movable contacts operat ing to establish connection between said line and an idle link-circuit, driving means for advancing said contacts in one direction to bring about such connection,restoring means for moving said contacts in the reverse direction to disconnect said line, and means responsive to current in both limbs but not to current in the active limb alone for causing the operation of said switch whereby said line is connected. l

58. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a travel ing switch and associated driving and con trolling means for establishing connection between said line and an idle link-circuit,

and an electrically operated switch in a local circuit operating to disconnect said active limb from said source, said switch be ing'automatically operated in response to current in said active limb but not in response to current in both limbs.-

,59. A. telephone exchange-system comprising a grounded "source of'current, a plurality of link-circuits, a-telephone line having an active limb *nornmlly connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a travelingswitch and associated driving and 'controlling means for establishing connection between said line and an idle link-circuit, an electrically operated. switch in a local circuit operating to disconnectsaid active ing switch having movable contacts operat ing to establish connection between said line and an idle link-circuit, driving means for advancing said contacts in one direction to bring aboutsuch connection, restoring means for moving said contacts in the reverse direction to disconnect said line, and a controlling line relay for said switch so connected that an abnormal earth connection to the'active limb does not caiasevthe operation of said driving means.

61. l A telephone exchange system comprising a grounded source of current, a plurality of'link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch and an associated driving and controlling means for establishing connection betweensaid line and an idle link-circuit, and a line relay and a local relay for controlling said switch so connected that an abnormal earth connection to the active limb will not cause said operation of said switch. I

62. Atelephone exchange system comprising a grounded source-of current, a plurality of link-circuits, a telephone line having an active limb. normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch having movable contacts operat ing to establish connection between said line and an idle link-circuit, driving means for advancing said contacts in one direction to bring about such connection, and a relay for each line limb for controlling said switch and circuit connections whereby an abnormal earth connection to the active limb does means.

ingan active limb normally connected to the active terminal of said source and an opposlte limb" normally connected to the grounded termlnal of said source, a travelmasses ing switch and associated driving and controlling means for establishing connection between said line and an idle link-circuit, andarelay for each line'limb to control said switch and circuit connections whereby an abnormal earth connection to the active limb does not cause said operation of said switch.

64. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch and associated driving and controlling means for establishing connection between said line and an idle link-circuit, and an electrically operated switch for disconnecting the active line limb from said source whereby an abnormal circuit for the line limbs doesnot cause a link-circuit to be permanently excluded from selection by the switches of. other normal lines.

65. A telephone exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected t6 the active terminal of said source and an opposite limb normally connected to the grounded terminal of said source, a traveling switch and associated driving and controlling means for establishing connections between said line and an idle link-circuit, and an electrically operated switch for dis connecting the active .linelimb from said source and an operators key for controlling said electrically operated switch whereby an abnormal circuit for the line limbs'does not cause a link-circuit to be permanently excluded from selection by the switches of other normal lines.

66. A telephone exchange system comprising a telephone line extending from a substation to an exchange, a plurality of associated link-circuits, a traveling switch having movable contacts operating to establish connection between said line and an idle link-circuit, driving means for advancing said contacts in one direction to bring about such connection, restoring 'm'cans for movmg said contacts in the reverse direction to disconnect said. line, and a line relay,-'-alocal relay andcircuit connections whereby a short circuit of the line is prevented from causing a link-circuit to be permanently occupied to the exclusion of normal similar lines,

67. A telephone. exchange system comprising a grounded source of current, a plurality of link-circuits, a telephone line having an active limb normally connected to the active terminal of said source and an opposite limb normally connected to the grounded terminal of source a traveling masses switch and associated driving and controlling means for establishing connection between saidline and an idleilink-circnit, other telephone lines and manual means for connecting a selected link-circuit to one of i said other telephone lines, and means whereby when the line is connected to a link-circuit and circuit is closed through the line limbs an operator may cause the active limb of the line to be disconnected -from said central source.

68. A telephone exchange system comprising a telephone line extending from a substation to an exchange, a plurality of associated linlccircuits, a traveling switch having movable'contacts operating to connect an idle link-circuit and said line, other telephone lines and manual means for connecting a selected linlncircuit to one of sald other telephone lines, driving means for said switch, restoring means for said switch, and means whereby when the line is connected to a link-circuit and circuit is closed through the line limbs an operator may cause the operation of said restoring means.

69. A; telephone exchange system comprising a; telephone line extending from a substation to an exchange, a plurality of associated link-circuits, a traveling switch having movable contacts operating to connect an idle link-circuit and said line, other telephone lines, and manual means for connecting a selected link-circuit to one of said other telephone lines, driving means for said switch, and means whereby when the 'line is connected to a link-circuit and circuit is closed through the line limbs an operator may cause said switch contacts to move to their normal position and come to rest.

70. A telephone exchange system comprisin g a grounded source of current, a plurality of link-circuits, a telephone line having an whereby when the line is connected to a link-- ro gh the line 2 operation disconnec- ,l.'minal of circuit and circuit is closed t limbs an operator may cause of said restoring means and tn tion of the line from the active said source.

71. A telephone system comprising a telephone line, link-circuits, a traveling switch for uniting said line and an idle one of said link-circuits, two electromagnets normally under line-circuit control, a source of current connecting the windings of said electromagnets in series with each other and with 6% the line, driving mechanism for the moving contacts of said switch controlled by one of said electromagnets. and a test circuit for determining the selection of an idle link-circuit controlled by said second electromagnet. 7d

72. A. telephone system comprising a telephone line, link-circuits, a traveling switch having line and local contacts for uniting said line and an idle one of'said link-circuits, two electromagnets normally under line-circuit control driving mechanism for the moving switch-contacts controlled by one of said magnets, a test circuit extending to the'movable local contact of said switch and controlled by said second-magnet, and a third electromagnet actuated upon the con nection of said line and an idle link-circuit to stop said driving means.

73. A telephone system comprising a telephone line, link-circuits, a traveling switch having line and lozal contacts for uniting said line and an idle one of said link-ch cuit s, two electromagnets normally under linecircuitcontrol,'driving mechanism for the moving switch-contacts controlled by one of said magnets, a test, circuit extending to the movable local contact of said switch and controlled by said second magnet. and i a relay having -normally open contacts through' which the limbs of said telephone line extend to said switch line-contacts, and means for actuating said relay to close said contacts and to stop, said driving means upon the connection of said line and idle linlc, circuit. i

74. A telephone system comprising a telephone line, link-circuits, a traveling switch for uniting said line and an idle one'ot said-v linkcircuits, two control electromagnetic normally under linccircuit control; driving lull.

mechanism for the moving contacts of said switch controlled by one of said magnets, a manual connection terminal for said line, and a test circuit for determining the selecting operation of said switch and a test'conlia nection for said terminal both controlled-by said second magnet.

7 A. telephone system comprising a telephone line, linlccircuits, a taveling switch for uniting said line and an idle one of said, link-circuits, two control electromagnets normally under line-cirZ-uit c'6ntrol,mdriving mechanism for-the moving contacts of said switch controlled by one of aid nn igncts, a manual connection terminal for said line, 128 a test circuit for determining the selecting. operation of'said switch and a test connec tion for said terminal both controlled by said second magnet, and a cut-oil relay associated with said terminal and operative to v disconnect said magnets from said line.

7 6. A telephone system comprising a telephone line, link-circuits, a traveling SWltClL for uniting saici line anti an idle one of said minai both concrolled by said sccomi link-circuits, 6W0 cnntiol Electromagnets norr and by said cu-oif relay. 10 many under fine-circuit control, driving In witnes whereof, 1 hereunto subscribe mechanism for the moving cow-acts of said 1y name this 17 day of September, 1906.

5 switch controlled by one of said magnets, 21 HARRY Gr. WEBSTER.

manual connection terminal for said line, a Witnesses: cut-01f relay associated With said terminal, 'H. (J. OLMSTEAD,

and test connections for said switch and f0: Gm. lVIUI-TLLE). 

